The planet Mars has been hiding out for months. It passed behind the Sun early this year, and it's taken a while to emerge from the Sun's glare. But it's finally doing so, pulling into view in the early morning sky.

Tomorrow, in fact, it's pretty easy to find because it has a prominent companion: the Moon. Mars looks like a bright orange star a little below the Moon at first blush of twilight.

Mars is known as the Red Planet because orange dust covers much of its surface. But early in its history, Mars was much warmer and wetter than it is today. A giant ocean may have covered a good bit of its surface. So at least from some angles, Mars might have looked not red or orange, but blue.

It's possible that Mars could also be a lot bluer in the future -- and greener, too. Scientists and engineers have talked about ways to terraform the planet -- to remake it as a world that's comfortable for life. It would be a big, complicated, and expensive undertaking, though -- something that's not going to happen anytime soon.

Before then, people would have to live in small bases on Mars. But those, too, would need a lot of blue and green. Inhabitants could find the blue -- water -- on Mars itself. And they could bring the green from Earth -- seeds to grow in greenhouses. Biologists have been experimenting with designing plants to survive Martian conditions -- making it easier to introduce a little green on the Red Planet.